It has been proposed to use mobile stations instead of credit cards at a point of sale. In this proposal, it has been suggested that a wireless link be established between the point of sale device and the mobile station. The mobile station may provide the point of sale device with similar information to that provided by a credit card.
One problem with this proposal is how to ensure that the correct mobile station is connected to the point of sale device. For example, in a busy supermarket, there may be a large number of point of sale devices and a large number of mobile stations. It is important that the right point of sale device be connected to the right mobile station. Clearly, considerable problems would be caused if the wrong mobile station were connected to the wrong point of sale device. The user of a mobile station could be charged for goods not purchased by the user.